Manley Chinook - chronic issues

Did you buy this new from Upscale? Even used I think they warranty the used stuff for perhaps 90 days? When did this start or did it start in September? If so, I hate to mention the obvious but that piece should have gone back as soon as those demons raised their ugly head.
I say no to tubes as I cannot believe you keep coming up with bad tubes every time you swap one out. Are all the soldered joints that hold the tube sockets to the board solid? It sounds to me that somewhere their is a bad or loose connection that is allowing some DC to run amok in the unit. Did you call Manley? The people there are pretty good about diagnosing the issues over the phone but it sounds to me that the Chinook is going to need a trip back to the factory for a good "once over". It is at times amazing how a small piece (resistor etc.) can go bad and make a mess of the whole unit. I once had a $1.25 resistor turn a whole preamp into a boat anchor. The same with a transformer that went south. If tube replacements did not cure the problem then the issues is probably beyond the skills of mere mortals and the manufacturer needs to eye-ball it.
riley804 called it. The Chinook needs a trip home, sorry to say but there is a lot that goes on in the Chinook and you do not want to be messing with it.

Manley is a good company. The chinook is a good product that is typically very reliable. Obviously you have an occult problem somewhere in that preamplifier, and like everyone else said it is probably very minor, if and when it is properly identified. Complaining here on Audiogon is not going to help you one bit. You need to contact upscale audio and or Manley, and I am sure they will solve the problem.

Over the years have had two chinooks. Both were trouble free with MM or MC carts. unit is well made. would wonder  if yours got dropped in shipping.

would return to manley have them look at it.

Check your earthing connections. I had a similar problem with my Manley Steelhead, and the solution was to connect everything really tightly to one single earthing point.